1. Field of the Invention
This invention relates to an apparatus and a method for treating the tissue lining of a human body cavity, particularly the endometrium of the uterus. More specifically, the apparatus and method of the present invention provides improved treatment, e.g., cauterization of the endometrium of a mammalian uterus, without many of the disadvantages and dangerous features of known techniques.
2. The Prior Art
The following terms as used herein have the meaning given below:
"Cauterization" means the application of heat to tissue in an amount sufficient to destroy the tissue.
"Necrosis" means the death of cells in tissue.
"Endometrium" is that portion of the inner lining of the uterus to which an embryo normally attaches and excludes the portions of the uterine inner lining forming the cervix, to which the embryo usually does not attach.
Apparatus and methods for cauterization of the endometrium of a mammalian uterus, useful in sterilization procedures and cancer treatments, are well known. Thermal and cryogenic treatments have been utilized in such cauterization techniques and typically involve either the direct or indirect application of heat or cold to the tissue to be treated.
For example, a laser hysteroscope has been used to cauterize the endometrial layer of the uterus. This laser treatment suffers from several disadvantages. It requires the application of an intense amount of thermal energy to a relatively small area of tissue even though such a large amount of heat may not be necessary to effectively cauterize the tissue. Further, this laser treatment requires the physician to continually reposition the laser used in the treatment within the uterus in order to treat the entire endometrium. Such internal manipulation of a laser hysteroscope within the uterus of a patient is both difficult, requiring a significant level of skill to perform, and potentially dangerous. Accidental puncture of the uterine or tissue wall may result from manipulation of the laser scope within the uterus or body cavity, and tissue layers beneath the endometrium may be burned if a laser's beam is left focused on one area of tissue for too long a period of time.
A variety of alternatives to laser treatment in cauterizing the uterine endometrium are known. In U.S. Pat. No. 3,924,628, Droegemueller et al. disclose a method and apparatus for necrosing tissue cells that utilizes an extendable bladder which is inserted in the uterus and filled with a circulating fluid or gas at cryogenic temperatures (referring to temperatures sufficiently low to cause cell necrosis). The bladder disclosed by Droegemueller et al. is maintained in substantially continuous contact with the inner surface of the uterine lining and is said to achieve necrosis of substantially all of the uterine endometrium in a single treatment. Droegemueller et al. disclose the use of liquid nitrogen that vaporizes prior to introduction into the bladder, thereby pressurizing the bladder to a level which ensures adequate contact with the uterus. Other fluids disclosed by Droegemueller et al. as useful in their method include refrigerants such as freon. Droegemueller et al.'s method and apparatus suffers from the disadvantage of employing cryogenic fluids which could prove toxic to a patient in the event of bladder rupture. Moreover, Droegemueller et al.'s apparatus does not allow precise regulation of the pressure used to inflate the bladder. Another disadvantage of Droegemueller et al.'s technique is that cryogenic necrosis of the endometrium occurs at extremely low temperatures that pose a threat to tissue layers adjacent to the uterine endometrium. Droegemueller et al. and similar cryogenic techniques also require the use of expensive equipment such as compressors and insulated vessels associated with the storage and transmission of refrigerants. Moreover, Droegemueller et al.'s technique may require warming of the bladder in order to remove it from the body and minimize tearing of the surrounding tissue which has adhered to the bladder during the freezing process.
In U.S. Pat. No. 2,734,508, Kozinski discloses a therapeutic apparatus for applying dry heat to body cavities comprising an applicator that is introduced in the body cavity while deflated and which is subsequently inflated and heated by means of circulating hot air. Kozinski does not disclose an applicator which conforms to the shape of a body cavity. Further, given the lower heat transfer coefficients of gases as compared with liquid, treatment with Kozinski's apparatus should involve a long period of time in order to achieve necrosis, thereby exposing the patient to additional discomfort and risk. Moreover, Kozinski's apparatus does not provide for measurement and regulation of internal pressures and temperatures of the applicator introduced.
U.S. Pat. No. 2,077,453, issued to Albright, discloses a therapeutic appliance comprising a relatively long tubular applicator which is shaped and formed generally to the passage into which it is to be inserted and which has relatively thin elastic rubber walls that transfer heat and which distend to fit irregularities of the treated areas upon application of internal pressure. Albright also discloses that fluids such as heated water could be utilized as a heating means in his applicator. The applicator of Albright, like that of Kozinski, however, suffers from the disadvantage that the distension of its walls to conform to the irregularities of the endometrium is limited as Albright provides an integral rubber web which serves to prevent undue distension of the applicator. Moreover, Albright requires that the fluid be circulated throughout the apparatus. Albright also does not provide an apparatus that allows regulation of temperature and pressure of the fluid or other bladder inflation means.
U.S. Pat. No. 3,369,549, issued to Armao, discloses a therapeutic device for applying heat or cold to body cavities comprising a capsule probe containing a heat exchanger and a flexible bladder that can be inflated to conform to a body cavity. Armao does not, however, disclose a control means for regulating the temperature and pressure of the flexible applicator, nor does he disclose cauterizing tissue in the cavity being treated.
Other patents that disclose the use of thermal treatment of the interior lining of a body cavity include U.S. Pat. Nos. 2,192,768; 2,466,042; 2,777,445; 3,369,549, and 4,949,718.